Field of the Invention
The present invention relates to a portable display device and an operation detecting method.
Description of the Related Art
Heretofore, there has been a portable display device that detects acceleration changes occurring due to light touch (tap) operations on a display screen and/or a chassis to perform processing. In order to detect such tapping operations (hereinafter described as “taps”), acceleration waveforms obtained by the acceleration sensor are usually sampled to analyze waveforms corresponding to taps (for example, see Japanese Patent Application Laid-Open Publication No. 2009-278294, which corresponds to U.S. Pat. No. 8,587,530 B2).
However, because the portable display device moves while being carried by a user, accelerations relevant to movements of the portable display device itself are added to changes of accelerations relevant to taps. Japanese Patent Application Laid-Open Publication No. 2012-146156, which corresponds to US2012/0185203A1, therefore discloses the technique to previously define magnitudes of acceleration amplitudes corresponding to taps and/or ranges of amplitude frequencies, and perform operations while distinguishing the changes of accelerations relevant to taps from changes of accelerations relevant to other factors such as drop and collision.
However, the detecting process becomes complicated when detecting the waveform by frequency analysis in the case that periodical changes of accelerations overlap with changes of accelerations relevant to taps, the periodical changes occurring in the portable display device when a user thereof travels, especially runs, while holding the portable display device in his/her hand and/or wearing the same on his/her body. Meanwhile, in the case of detecting taps, especially double taps as two continuous tap operations, from time-series data, if a detection criterion is set loosely, misdetections in a state of standing still increase. If the detection criterion is set severely, tap operation detection becomes difficult during the movement.
The present inventions are a portable display device and an operation detecting method which are capable of easily and properly detecting double taps depending on a movement state of a user of the portable display device.